This application claims benefit of Japanese Application No.2000-086994 filed in Japan on Mar. 27, 2000, the contents of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to a translucent screen, and more particularly to a translucent screen which can display a projected image so as to be observed.
2. Description of the Related Art
Various configurations have been proposed for translucent screens used in equipment where images are projected onto a translucent screen by a projector so that images can be observed.
In the case of a translucent screen stated in Japanese Patent Application Laid-Open No. 10-90797, for example, in order to improve the drop of the peripheral light quantity by light entering at an angle onto the peripheral area of the screen in a rear projection type projector, which screens are becoming progressively larger and slimmer, many beads, which are spherical optical materials, are arranged on the main surface of the transparent substrate at the projector side, and the luminous flux emitting side of the beads, which is the transparent substrate side, is retained by the beads retaining layer, and a concentric type optical layer is created at the luminous flux incident side, which is closer to the projector than the beads, and the luminous flux entering diagonally is deflected so that the light enters the beads approximately vertically.
Japanese Patent Application Laid-Open No. 5-273655 describes a technology to decrease the reflection of extraneous light by creating a colored layer which absorbs light having a predetermined wavelength range in the translucent screen where many beads are arranged on a plane.
Also U.S. Pat. No. 5,563,738 and U.S. Pat. No. 5,781,344 describes a technology to arrange many beads on the main surface at the projector side of the transparent substrate, retaining the luminous flux emission side of the beads with a bonding layer, and creating a new resin layer at the luminous flux incident side, which is at the projector side of the beads, so that an effective radius of the curvature at the rear side of the beads is increased and the reflection of extraneous light is decreased.
On the other hand, to implement a multi-screen, a technology to project images of a plurality of arranged projectors onto a translucent screen has been proposed. The images to be projected by the plurality of projectors may be independent and different from each other, but it is also possible to display a large image on the entire screen by projecting a divided part of one image by each projector.
To implement such a multi-screen, a plurality of projectors P1, P2, P3 . . . are arranged so as to project images on the translucent screen 91 having a diffusion surface, which is observed.
The above projector comprises, for example, a translucent LCD which displays images, an illuminating system which illuminates this LCD from the rear face, and an optical system which projects the images of the illuminated LCD onto the above translucent screen, and the projected luminous flux is illuminated and spread in a fan shape from the optical system onto the translucent screen.
In the above mentioned configuration, generally smooth and continuous images can be observed when the projected images are observed from the right front of the screen, but if the projected images are observed from a diagonal direction, the connecting sections of the images which are projected by different projectors are observed with discontinuous brightness, as shown in FIG. 23.
In other words, as FIG. 22 shows, the luminous flux transmitted through the screen 91 is diffused on the diffusion surface, and at this time, the intensity of light which is diffused in the direction the same as the incident light is the strongest, and intensity gradually decreases as the angle of the diffused light recedes from this direction.
Therefore in FIG. 21, the beam R1 projected from the projector P2 is emitted at a relatively high intensity after transmitting the screen 91 as a beam R1xe2x80x2, which is almost the same direction as the beam R1. If the beam R2 projected from the projector P1 is observed from the direction of beam R1xe2x80x2, however, the intensity of beam R2xe2x80x2, which is the same direction as the beam R1xe2x80x2 after diffusion, drops, so as FIG. 23 shows, the connecting sections of the images 91a by each projector are observed as discontinuous, where the section contributed by beam R1xe2x80x2 has high brightness and the section contributed by beam R2xe2x80x2 has low brightness.
It is an object of the present invention to provide a translucent screen where smooth continuous images can be observed even from a diagonal direction.
The present invention is a translucent screen used for a projector system which creates a multi-screen by projecting respective images from a plurality of arranged projectors, comprising a first surface where a plurality of condensing optical surfaces for condensing entering luminous flux are arranged at a predetermined cycle, and a second surface where a plurality of optical surfaces for deflecting the optical paths of lights entering approximately the center of the condensing optical surfaces arranged on the first surface to the direction approximately vertical to the main surface of the translucent screen are arranged at a predetermined cycle, wherein the above mentioned first surface and the second surface are set such that when the same images are projected from two adjacent projectors out of the above mentioned plurality of projectors, the beams from the two adjacent projectors emitted from the second surface are set such that brightness is the same regardless the direction of observing the translucent screen, and that the images constituting the multi-screen continue smoothly.
The objects and advantages of the present invention will become further apparent from the following detailed explanation.